4,402 research outputs found
Time variability of TeV cosmic ray sky map
The variation in the intensity of cosmic rays at small angular scales is
attributed to the interstellar turbulence in the vicinity of the Solar system.
We show that {a turbulent origin of the small-scale structures implies that}
the morphology of the observed cosmic-ray intensity skymap varies with our
location in the interstellar turbulence. The gyroradius of cosmic rays is shown
to be the length scale associated with an observable change in the skymap over
a radian angular scale. The extent to which the intensity \mpo{at a certain}
angular scale varies is proportional to the change in our location with a
maximum change of about the amplitude of intensity variation at that scale in
the existing skymap.} We suggest that for TeV cosmic rays a measurable
variation could occur over a time scale of a decade due to the Earth's motion
through the interstellar medium, if interstellar turbulence persists down to
the gyroradius, \mpo{about for TeV-ish cosmic rays}.
Observational evidence of the variability, or an absence of it, could provide a
useful insight into the physical origin of the small-scale anisotropy
Characterization and Verification Environment for the RD53A Pixel Readout Chip in 65 nm CMOS
The RD53 collaboration is currently designing a large scale prototype pixel
readout chip in 65 nm CMOS technology for the phase 2 upgrades at the HL-LHC.
The RD53A chip will be available by the end of the year 2017 and will be
extensively tested to confirm if the circuit and the architecture make a solid
foundation for the final pixel readout chips for the experiments at the HL-LHC.
A test and data acquisition system for the RD53A chip is currently under
development to perform single-chip and multi-chip module measurements. In
addition, the verification of the RD53A design is performed in a dedicated
simulation environment. The concept and the implementation of the test and data
acquisition system and the simulation environment, which are based on a modular
data acquisition and system testing framework, are presented in this work
The combined absence of NF-kappa B1 and c-Rel reveals that overlapping roles for these transcription factors in the B cell lineage are restricted to the activation and function of mature cells
Transcription factors NF-KB1 and c-Rel, individually dispensable during embryogenesis, serve similar, yet distinct, roles in the function of mature hemopoietic cells. Redundancy among Rel/ NF-KB family members prompted an examination of the combined roles of c-Rel and NF-KB1 by using mice that lack both proteins. Embryonic development and the maturation of hemopoietic progenitors were unaffected in nfkb1(-/-)c-rel(-/-) mice. Peripheral T cell populations developed normally, but follicular, marginal zone, and CD5(+) peritoneal B cell populations all were reduced. In culture, a failure of mitogen-stimulated nfkb1(-/-)c-rel(-/-) B cells to proliferate was caused by a cell cycle defect in early G(1) that prevented growth. In vivo, defects in humoral immunity and splenic architecture seen in nfkbl(-/-) and c-rel(-/-) mice were exacerbated in the double mutant mice. These findings demonstrate that in the B lineage overlapping roles for NF-K81 and c-Rel appear to be restricted to regulating the activation and function of mature cells
SIZING HYDRAULIC STRUCTURES IN COLD REGIONS TO BALANCE FISH PASSAGE, STREAM FUNCTION, AND OPERATION AND MAINTENANCE COST
The purpose of this research was to evaluate how characteristics of hydraulic structures, such as slope or size, used at crossings over waterways relate to operation and maintenance (O&M) effort, fish passage, and stream function. Data on O&M concerns, fish passage concerns, and crossing characteristics were collected from 45 road-stream crossings in Prudhoe Bay, Alaska, during lower and higher water periods in both 2014 and 2015 (four events total). Logistic regression and generalized mixed models were used to examine relationships between O&M effort (response) and five explanatory variables. For all data from all years combined, there were no observable associations among O&M and culvert type or constriction ratio. However, lower constriction ratios were observed for sites with O&M needs in the June 2014 data set. The proportion of sites with both fish passage and O&M concerns was 0.52; comparatively, the proportion of sites with no fish passage concern but with O&M concern was 0.35
A method for precise charge reconstruction with pixel detectors using binary hit information
A method is presented to precisely reconstruct charge spectra with pixel
detectors using binary hit information of individual pixels. The method is
independent of the charge information provided by the readout circuitry and has
a resolution mainly limited by the electronic noise. It relies on the ability
to change the detection threshold in small steps while counting hits from a
particle source. The errors are addressed and the performance of the method is
shown based on measurements with the ATLAS pixel chip FE-I4 bump bonded to a
230 {\mu}m 3D-silicon sensor. Charge spectra from radioactive sources and from
electron beams are presented serving as examples. It is demonstrated that a
charge resolution ({\sigma}<200 e) close to the electronic noise of the ATLAS
FE-I4 pixel chip can be achieved
Neutron irradiation test of depleted CMOS pixel detector prototypes
Charge collection properties of depleted CMOS pixel detector prototypes
produced on p-type substrate of 2 kcm initial resistivity (by LFoundry
150 nm process) were studied using Edge-TCT method before and after neutron
irradiation. The test structures were produced for investigation of CMOS
technology in tracking detectors for experiments at HL-LHC upgrade.
Measurements were made with passive detector structures in which current pulses
induced on charge collecting electrodes could be directly observed. Thickness
of depleted layer was estimated and studied as function of neutron irradiation
fluence. An increase of depletion thickness was observed after first two
irradiation steps to 110 n/cm and 510
n/cm and attributed to initial acceptor removal. At higher fluences the
depletion thickness at given voltage decreases with increasing fluence because
of radiation induced defects contributing to the effective space charge
concentration. The behaviour is consistent with that of high resistivity
silicon used for standard particle detectors. The measured thickness of the
depleted layer after irradiation with 110 n/cm is more than
50 m at 100 V bias. This is sufficient to guarantee satisfactory
signal/noise performance on outer layers of pixel trackers in HL-LHC
experiments
Observation of Long-Lived Muonic Hydrogen in the 2S State
The kinetic energy distribution of ground state muonic hydrogen atoms
mu-p(1S) is determined from time-of-flight spectra measured at 4, 16, and 64
hPa H2 room-temperature gas. A 0.9 keV-component is discovered and attributed
to radiationless deexcitation of long-lived mu-p(2S) atoms in collisions with
H2 molecules. The analysis reveals a relative population of about 1%, and a
pressure-dependent lifetime (e.g. (30.4 +21.4 -9.7) ns at 64 hPa) of the
long-lived mu-p(2S) population, equivalent to a 2S-quench rate in mu-p(2S) + H2
collisions of (4.4 +2.1 -1.8) 10^11 s^-1 at liquid hydrogen density.Comment: 4 pages, 2 figures, accepted for publication in Physical Review
Letter
BDAQ53, a versatile pixel detector readout and test system for the ATLAS and CMS HL-LHC upgrades
BDAQ53 is a readout system and verification framework for hybrid pixel
detector readout chips of the RD53 family. These chips are designed for the
upgrade of the inner tracking detectors of the ATLAS and CMS experiments.
BDAQ53 is used in applications where versatility and rapid customization are
required, such as in laboratory testing environments, test beam campaigns, and
permanent setups for quality control measurements. It consists of custom and
commercial hardware, a Python-based software framework, and FPGA firmware.
BDAQ53 is developed as open source software with both software and firmware
being hosted in a public repository.Comment: 6 pages, 6 figure
The Real World of Ventilation Troubleshooting: A Swine Case Study
Swine finishing facility ventilation has become relatively complex and is often mismanaged as a system. One of the few ways to truly understand these systems is to spend time systematically going through the many components of the building. To learn to help producers better, a team of university Extension specialists that included agricultural engineers and animal scientists spent an extended period carefully documenting conditions in a deep-pit swine finishing building with two 1,000-head rooms. Exhaust fans in the pit and walls operated at various stages throughout the year as a negative-pressure ventilation system. A computerized controller activated exhaust fans, a ventilation curtain actuator, and heaters. Gravity baffled ceiling inlets were evenly spaced in the building to provide good air distribution during cold and mild weather conditions. Following the review of current conditions and operating parameters, performance deficiencies were identified and recommendations were given regarding controller settings, inlet settings, and curtain management. The overall operating characteristics of the ventilation system and air quality in the animal space were documented ventilation and related management changes were discussed with the owner/operator
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